A method of washing an aspiration probe of an in-vitro diagnostic system is disclosed. The aspiration probe comprises an outer surface and an inner surface forming an inner space for receiving a fluid. The method comprises dipping the aspiration probe into a first wash fluid so that the outer surface is immersed at least in part into the first wash fluid, aspirating an amount of the first wash fluid into the inner space of the aspiration probe, propagating an ultrasonic vibration to the outer surface of the aspiration probe via the first wash fluid, and rinsing the outer surface and the inner surface of the aspiration probe with a second wash fluid. Further, an in-vitro diagnostic method and an in-vitro diagnostic system are disclosed.